As the House of Commons debated the new law to ban supposed incitement to religious hatred, Boris Johnson yesterday gave a remarkably good performance. As he bravely but absolutely correctly noted, being vicious, crude and nasty about a religion is not a liberty anyone who cares about religious truth itself should flinch from defending.

If a religion is worth believing in, it ought to be strong enough to withstand the most scurrilous and monstrous attacks. If a religion is worth believing in, those assaults should diminish the critics and not the religion itself. Whether or not a religion is worth believing in, it is the sovereign right of every human being to say what exactly he or she thinks of it.

Boris continues, noting that the bill restricts the liberties not only of those who wish to criticise particular religions, but those who wish to make the case for particular faiths too.

Let me put this as tactfully as I can. Despite the best efforts of the ecumenists, we live in a world of mutually antagonistic faiths. We have heard representatives of various faiths in the Chamber this evening. They do not merely advertise the exclusive benefits of their own paths to salvation. They also indulge in a great deal of negative campaigning, in the manner of soap brands, or indeed political parties, against their main rivals.

How wise. It is precisely a part of the recruiting power of any system of belief - not only religious but political, spiritual, personal - that one can explain the grave deficiencies of the alternative. If you can't legally say that, for example, banning the eating of pork is a bloody stupid idea, then your liberty to argue as to why Christianity is the truth is woundingly diminished.

But the real flourish came as Boris turned to the faith whose appeasement everyone knows is behind this legislation. What did he do to conclude his speech? He read from the Koran.

Reciting in full passages calling for all manner of monstrous treatment for the Christian, for the Jew, for the unbeliever, he challenged government ministers to explain precisely how those passages were anything other than 'incitement to religious hatred'. That they could not answer is proof that this law is exactly about limiting religious expression even (if there is any real logic to the legislation) to the extent of censoring the holy books of faiths with which many of us profoundly disagree, but for which no decent, non-totalitarian person wants legal prohibition.